On the Mosul Front, a Brutal Battle Against ISIS and Time

Mr. Gordon, a military correspondent for The Times, is working with the Iraqi reporter Kamil Kakol on the front lines in Iraq.

Clambering onto a rooftop with a small group of soldiers from Iraq’s counterterrorism service, we scanned the Islamic State’s stronghold in western Mosul as one of its armored car bombs maneuvered toward the front line.

Within minutes, there was an enormous explosion — a shoot of red flame and a funnel of black smoke that reached into the sky.

This time, at least, there were no friendly casualties. The Iraqi troops who were clawing their way forward in the streets below had piled enough debris ahead of them that the suicide driver was stopped short of his target. All over the city, you can see that kind of wreckage and ad hoc barriers, put up by both sides.

Every day, for weeks, the battle to take western Mosul from the Islamic State has looked like this: a block-by-block crawl as casualties mount.

The militants are contesting every move by the counterterrorism forces, and they are making full use of the hundreds of thousands of civilians still trapped in their strongholds.

“If the city was empty of civilians, we could have been done with our mission a long time ago,” said Lt. Gen. Abdul-Wahab al-Saadi, a senior commander with the counterterrorism service.

The plight of civilians appears to be worsening by the day, adding to commanders’ urgency to find some edge against the Islamic State here.

The Iraqis do not have the luxury of conducting a siege: Prime Minister Haider al-Abadi has told his generals that dragging out the Mosul operation, now in its seventh month, would work only to the advantage of the Islamic State, which many in the West call ISIS or ISIL, but the Iraqis call Daesh.

This was not the mission that American military commanders envisioned for the counterterrorism service when they established it after the United States invasion in 2003. The force’s original mission was to conduct lightning raids against terrorists and insurgents.

“The CTS has made enormous sacrifices since 2014, and many of the old hand are dead, killed in Anbar Province and elsewhere,” said David M. Witty, a retired colonel with the United States Army Special Forces and former adviser to the counterterrorism service, known as CTS.

The militants’ basic strategy appears to be to focus much of their efforts on blunting the CTS attack, calculating that if they can stymie Iraq’s most experienced fighting force, the Iraqi government’s broader offensive will bog down. Now, the CTS is fighting on a southern front just to the west of Iraq’s federal police and other Interior Ministry troops.

General Saadi, a senior CTS commander, invited me to come with him to the front in his armored Humvee. We carefully navigated past the wreckage of car bombs and hastily constructed barriers made of sand or abandoned cars.

Along the way, he showed me his tactical iPad, displaying the locations of all the friendly forces, his own position and the streets in the city.

When we started the drive, there was a smattering of civilians, some of whom had marked their houses with white flags. By the time we got to the Tanak section of the city, civilians were nowhere to be seen. Tanak was no longer a neighborhood — it was terrain.

We got out of the vehicles in Tanak and entered an abandoned house with a small courtyard, where we encountered a small group of soldiers. None wore body armor; most seemed to favor bandannas over uniforms.

There were no advisers from the American-led coalition in sight. A small team, with mine-resistant ambush-protected vehicles, was monitoring the fight from Yarmouk.

The Iraqi soldiers established a machine-gun position on the roof to provide covering fire for soldiers pressing the fight below.

None of this was lost on ISIS, which flew a reconnaissance drone over and sent a scout on a motorcycle to try to find the Iraqis’ position. Two American Black Hawk helicopters could be seen flying in the distance.

For hours, the two sides traded machine-gun fire. Young soldiers lugged heavy canisters of ammunition to the rooftop.

An aide to General Saadi, who used binoculars to monitor the fight and typed updates into the iPad, said that many of the Islamic State forces they had been battling were foreign fighters. From the bodies the Iraqis had recovered, he said, it appeared that many had not bathed in weeks.

“They don’t have a social life,” he said dismissively. “They just come here to fight and die.”

Eventually, enough seemed to be enough, and an American airstrike was called in to quell some of the enemy resistance. An Iraqi machine-gunner poured on the fire.

ISIS would not be silenced. A sniper fired a round toward the covered landing where the stairwell reached our rooftop, figuring that an Iraqi spotter and other personnel might be lingering inside.

It was a good guess: That is where the general’s aide and a few other journalists and I were sheltering. But we were low to the ground. The round was high and struck the back wall, splattering plaster, dust and tiny beads of glass into the air. One Iraqi cameraman took off his shirt to shake off the residue.

Video

A round fired by an Islamic State sniper struck a wall near us.

A battalion commander in a nearby counterterrorism unit was not so lucky that day: He was shot in the chest by a sniper and died.

On the drive back, we left the land of twisted wreckage and gradually rediscovered a small semblance of civilian life. There were small shops and children playing in the street. There was also a line of buses for residents looking to leave the city for refugee camps to the south.

General Saadi halted his Humvee and opened the heavily armored door to hand some food to an elderly beggar. But there was still more fighting to be done in the hours ahead, and tomorrow would be another day.

A version of this article appears in print on , on Page A10 of the New York edition with the headline: On the Mosul Front, a Block-by-Block Fight Against ISIS and Time. Order Reprints | Today’s Paper | Subscribe